This invention relates to pneumatic filling insertion in a loom, wherein the filling is supplied from a storage device located outside of the loom.
More particularly, pneumatic looms in the past have consisted of a number of types: in one type the filling is blown by a single nozzle and carried by a blast of air or jet stream through the shed. One disadvantage of this type is that the width of cloth which can be woven is limited due to a loss of flow velocity outside the nozzle at the potential jet core because the increasing turbulence within the surrounding boundry region of the jet stream which propels the filling. The turbulent air flow also causes the filling to untwist, so that only certain types of filling can be used. Still another disadvantage of this type of pneumatic loom is the large power consumption related to providing the necessary compressed air.
Another type of loom pneumatically stores yarn for several picks in a hollow projectile and propels the projectile mechanically through a shed. The size of the projectile still disallows high speed and it is a problem to draw yarn from the projectile uniformly. A more recent type of pneumatic loom has utilized a small shuttle more accurately referred to as a projectile to carry the free end of the filling through the warp shed. The filling end is either held mechanically within the projectile as shown for example in my U.S. Pat. No. 3,412,763 or held by friction as shown in my U.S. Pat. No. 3,395,737 where the filling is blown through a bore in the forward contour of the projectile during most of its flight. U.S. Pat. Nos. 3,831,640 and 3,868,976 show the projectile with blunt ends, where the filling is placed in one of the two annular chambers of the projectile in the form of a coil, so that the filling coils have a propensity to cling, and remain inside the said chamber during the larger portion of the flight. One disadvantage of this type of filling insertion is that the blunt shaped projectile cuts any warp yarns which protrude into the flight path of the projectile, which necessitates shutting down the loom and splicing the warp yarn. Also, the small annular chambers in the projectile limit the range of the weft yarn size.